1. Field of the Invention
The present invention relates to a polarizer and a manufacturing method thereof. In particular, it relates to a polarizer which is applied to a crystal liquid display device, an optical pick-up optical system, an optical element for optical communication or the like and which is suitable for effective utilization of reflected light, and a manufacturing method thereof.
2. Description of the Related Art
Generally speaking, a polarizer is known as an optical element which has a function of transmitting only linearly polarized light which is polarized in one direction and absorbing or reflecting linearly polarized light which is polarized in the direction perpendicular to the one direction. However, polarizers can be classified into multiple types depending on the configuration and the function thereof. In addition, since the features and characteristics for polarizers greatly differ depending on the type, suitable applications for them are also different.
Among these several types, polarizers of well known types are: a dye doped polymer polarizer which is manufactured by dispersing pigments of dichroic dye such as iodine in a high molecular weight film and stretching the film in a uniaxial direction; a doped glass-type polarizer which is manufactured by doping metal particulates such as silver on a glass and stretching the glass in a uniaxial direction; a metal wire polarizer which is made from metal wire having a periodic structure of a size which is equal to or lessr than wavelength, and a birefringent multi-layered film-type polarizer which utilizes multiple layer interference of a high molecular weight film having birefringence, and the like.
These polarizers of well known types are disclosed, for example, in Patent Literatures 1 to 5.
Specifically, Patent Literature 1 discloses a dye doped polymer polarizer as well as the manufacturing method thereof. According to the manufacturing method as disclosed in Patent Literature 1, a dye doped polymer polarizer is manufactured by adsorbing dichroic dye such as iodine in a macromolecule so as to form a thin film, and subsequently stretching the thin film in a uniaxial direction.
In addition, Patent Literature 2 discloses a metal wire polarizer as well as the manufacturing method thereof. According to the manufacturing method disclosed in Patent Literature 2, a reflective polarizer is manufactured by forming a metal wire having a periodic structure of a sub-wavelength size or less on a substrate.
Like Patent Literature 2, Patent Literature 3 discloses a metal wire polarizer as well as the manufacturing method thereof. According to the manufacturing method disclosed in Patent Literature 3, a reflective wire grid polarizer is manufactured through the use of dry etching while masking a polymer formed by the nano-imprint process.
In addition, Patent Literature 4 discloses a doped glass-type polarizer as well as the manufacturing method thereof. According to the manufacturing method disclosed in Patent Literature 4, a polarizer is manufactured by doping metal particulates such as cupper and silver in a glass and stretching the glass in a uniaxial direction.
Still further, Patent Literature 5 discloses a birefringent multi-layered film-type polarizer as well as the manufacturing method thereof. According to the manufacturing method disclosed in Patent Literature 5, a reflective polarizer is manufactured by laminating numbers of two types of high molecular weight films which have different refractive indexes on a substrate.
[Patent Literature 1] Japanese Patent Unexamined Publication No. Heisei 5-288929
[Patent Literature 2] Japanese Patent Unexamined Publication No. Heisei 9-304620
[Patent Literature 3] Japanese Patent Unexamined Publication No. 2006-84776
[Patent Literature 4] Published Japanese translation of a PCT Application 2001-501163
[Patent Literature 5] Japanese Patent Unexamined Publication No. 2006-178418